The XBox 360 is not a deal at all. You have to buy 24 months of Xbox Live for $15 per month. Or a total of $360 for 2 years for Xbox Live. You can buy 2 years for $100 ($50 per year) on amazon. Meaning you pay $260 + $99 = $360 for an Xbox 4GB Kinect Bundle which retails for $250. So basically you pay $100 more. What a scam by Microsoft to hit you with the $15 per month fee instead of the $50-$60 per year pricing.

For those that don't have $310 (250+60) available right away this is still fairly decent. The grand majority of retail consumers buy the initial item right away and then get the peripherals later.
$200 (Console)+$110 (Kinect)+$120 (Gold)=$430
$100 (Console)+$360 (Gold)=$460
A difference of less than 10%. Also, many people would be paying taxes on $310 using your suggested method of purchase. Going this route, only $100 would be taxed.